The research described in this proposal aims to investigate the molecular mechanisms involved in the abnormal iron accumulation observed in the disease, hereditary hemochromatosis (HH). In Specific Aim 1, the hypothesis that levels of SFT (Stimulator of Fe Transport) mRNA and protein are increased in the liver and duodenum of HFE-knockout mice will be tested. Because humans with HH lack functional HFE protein, the HFE-knockout mouse is the best available animal model for studying the human disease. Expression of SFT in various other tissues will also be measured to determine the pattern of expression of SFT. In Specific Aim 2, HeLa cells that over-express HFE will be transfected with SFT and transferrin-mediated iron uptake will be measured. The goal is to determine if increased expression of SFT will increase transferrin-mediated iron uptake, which has been found to be decreased in these cells. In Specific Aim 3, antisense strategies will be used to block the expression of SFT in HeLa cells, which do not express detectable levels of HFE. Specific Aim 3 will determine if the blocking of SFT expression will decrease transferrin-mediated iron uptake in these cells. Together, these specific aims will be useful in elucidating the molecular mechanisms involved in the abnormal iron metabolism of HH.